The Hemlock Lake Formation of the Saginaw Group is here named in the subsurface of the Michigan basin. The lower part of the formation is a sequence of thinly-bedded yellowish-gray sandstones, red and gray interbedded siltstones, and gray shales with minor carbonate rocks. A thin discontinuous coal is present at the base. The Six Lakes Limestone Member is present in the western part of the Hemlock Lake study area. The upper part of the Hemlock Lake consists of shale with minor amounts of siltstone, sandstone, carbonate rocks, and coal. The unit represents back-barrier and transgressive marine and alluvial plain deposits. Overlies the Parma Formation; underlies the Lake George Formation with sharp contact. Thickness at type well is 230 ft. Age is Early Pennsylvanian (Morrowan).

Source: GNU records (USGS DDS-6; Reston GNULEX).